A scanning Hall microprobe technique has been developed to measure the magnetic field around superconductors, and to make precision measurements of the]] critical state" profiles in single crystals of YBa2Cu 3O7-y. The field around a superconducting crystal has been calculated for the Meissner state and for the remanent state. This enables a quantitative analysis of the critical state profiles, and a novel method to determine JC. The invasion of magnetic flux above HC1 was examined and this provides direct evidence for the existence of a surface barrier to the entry of magnetic flux lines. The temperature dependence of JC was also measured and compared with that of the low TC material Nb0.5Ti0.5.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)